1. Field of the Invention
The invention relates to a switching device, notably for the control of an electrical motor which is part of the equipment of an automotive vehicle.
Such a switching device is provided in particular for being at the disposal of a user and/or the driver of the vehicle with a view to selecting the various operating speeds of an electric motor driving the fan of a heating and/or air-conditioning installation of the vehicle.
2. Object and Summary of the Invention
The object of the invention is such a device in which the actuating member is a rotary cylindrical knob placed such as to be partly protruding relative to one face of the instrument board and which, due to its characteristics, presents notably two qualities which are apparently contradictory; the first being that of allowing an easy manipulation of the actuating member by the user and/or the driver, the actuation of said member being carried out by exercising a very small effort, the second being that of ensuring an unequivocal selection of the various operating speeds of the fan motor by an accurate positioning of said member.
While exhibiting said two qualities, the device is very reliable and withstands the most severe conditions of utilization, particularly the vibrations which are permanent in an automotive vehicle running on a road.
The present invention allows ensuring a constant and permanent pressure of the brushes of a rotating member on the conductive tracks allowing the various electrical connections which are necessary for the control of the motor.
Also with a view to providing reliability, the invention provides a mounting of the device unit in the instrument board of the vehicle, without clearance in the three dimensions (lateral, vertical and longitudinal).
The design of the unit being directed by the laws prevailing in the automobile industry, viz. the smallest cost and a mass production, its various constituents are preferably obtained by molding plastics materials.
For the same reasons, another object of the invention is to allow the easy assembly of said constituents as well as a quick insertion of the unit in the instrument board to which it is destined.
Particularly, the rotating electrical switch device with an actuating knob is characterized in that the actuating knob which carries a slider contact is slidably and rotatably mounted on a small column which is part of a cage, a plate with electrical circuits with which cooperate this slider contact being also mounted on the small column and fixedly secured in position by snap-in engagement with the walls of the cage for providing a determined contact pressure between the slider contact and the circuits.